corejava第10版

corejava第10版/v2ch11/imageIO/ImageIOFrame.java

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+package imageIO;
+
+import java.awt.image.*;
+import java.io.*;
+import java.util.*;
+
+import javax.imageio.*;
+import javax.imageio.stream.*;
+import javax.swing.*;
+import javax.swing.filechooser.*;
+
+/**
+ * This frame displays the loaded images. The menu has items for loading and saving files.
+ */
+public class ImageIOFrame extends JFrame
+{
+   private static final int DEFAULT_WIDTH = 400;
+   private static final int DEFAULT_HEIGHT = 400;
+
+   private static Set<String> writerFormats = getWriterFormats();
+
+   private BufferedImage[] images;
+
+   public ImageIOFrame()
+   {
+      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
+
+      JMenu fileMenu = new JMenu("File");
+      JMenuItem openItem = new JMenuItem("Open");
+      openItem.addActionListener(event -> openFile());
+      fileMenu.add(openItem);
+
+      JMenu saveMenu = new JMenu("Save");
+      fileMenu.add(saveMenu);
+      Iterator<String> iter = writerFormats.iterator();
+      while (iter.hasNext())
+      {
+         final String formatName = iter.next();
+         JMenuItem formatItem = new JMenuItem(formatName);
+         saveMenu.add(formatItem);
+         formatItem.addActionListener(event -> saveFile(formatName));
+      }
+
+      JMenuItem exitItem = new JMenuItem("Exit");
+      exitItem.addActionListener(event -> System.exit(0));
+      fileMenu.add(exitItem);
+
+      JMenuBar menuBar = new JMenuBar();
+      menuBar.add(fileMenu);
+      setJMenuBar(menuBar);
+   }
+
+   /**
+    * Open a file and load the images.
+    */
+   public void openFile()
+   {
+      JFileChooser chooser = new JFileChooser();
+      chooser.setCurrentDirectory(new File("."));
+      String[] extensions = ImageIO.getReaderFileSuffixes();
+      chooser.setFileFilter(new FileNameExtensionFilter("Image files", extensions));
+      int r = chooser.showOpenDialog(this);
+      if (r != JFileChooser.APPROVE_OPTION) return;
+      File f = chooser.getSelectedFile();
+      Box box = Box.createVerticalBox();
+      try
+      {
+         String name = f.getName();
+         String suffix = name.substring(name.lastIndexOf('.') + 1);
+         Iterator<ImageReader> iter = ImageIO.getImageReadersBySuffix(suffix);
+         ImageReader reader = iter.next();
+         ImageInputStream imageIn = ImageIO.createImageInputStream(f);
+         reader.setInput(imageIn);
+         int count = reader.getNumImages(true);
+         images = new BufferedImage[count];
+         for (int i = 0; i < count; i++)
+         {
+            images[i] = reader.read(i);
+            box.add(new JLabel(new ImageIcon(images[i])));
+         }
+      }
+      catch (IOException e)
+      {
+         JOptionPane.showMessageDialog(this, e);
+      }
+      setContentPane(new JScrollPane(box));
+      validate();
+   }
+
+   /**
+    * Save the current image in a file.
+    * @param formatName the file format
+    */
+   public void saveFile(final String formatName)
+   {
+      if (images == null) return;
+      Iterator<ImageWriter> iter = ImageIO.getImageWritersByFormatName(formatName);
+      ImageWriter writer = iter.next();
+      JFileChooser chooser = new JFileChooser();
+      chooser.setCurrentDirectory(new File("."));
+      String[] extensions = writer.getOriginatingProvider().getFileSuffixes();
+      chooser.setFileFilter(new FileNameExtensionFilter("Image files", extensions));
+
+      int r = chooser.showSaveDialog(this);
+      if (r != JFileChooser.APPROVE_OPTION) return;
+      File f = chooser.getSelectedFile();
+      try
+      {
+         ImageOutputStream imageOut = ImageIO.createImageOutputStream(f);
+         writer.setOutput(imageOut);
+
+         writer.write(new IIOImage(images[0], null, null));
+         for (int i = 1; i < images.length; i++)
+         {
+            IIOImage iioImage = new IIOImage(images[i], null, null);
+            if (writer.canInsertImage(i)) writer.writeInsert(i, iioImage, null);
+         }
+      }
+      catch (IOException e)
+      {
+         JOptionPane.showMessageDialog(this, e);
+      }
+   }
+
+   /**
+    * Gets a set of "preferred" format names of all image writers. The preferred format name is the
+    * first format name that a writer specifies.
+    * @return the format name set
+    */
+   public static Set<String> getWriterFormats()
+   {
+      Set<String> writerFormats = new TreeSet<>();
+      Set<String> formatNames = new TreeSet<>(
+         Arrays.asList(ImageIO.getWriterFormatNames()));
+      while (formatNames.size() > 0)
+      {
+         String name = formatNames.iterator().next();
+         Iterator<ImageWriter> iter = ImageIO.getImageWritersByFormatName(name);
+         ImageWriter writer = iter.next();
+         String[] names = writer.getOriginatingProvider().getFormatNames();
+         String format = names[0];
+         if (format.equals(format.toLowerCase())) format = format.toUpperCase();
+         writerFormats.add(format);
+         formatNames.removeAll(Arrays.asList(names));
+      }
+      return writerFormats;
+   }
+}